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Abstract:

A method for controlling power in a battery-powered electronic apparatus
is disclosed. The electronic apparatus includes a battery, a detection
unit and a power consumption estimation unit. The battery supplies
electric power to each device within the electronic apparatus. The
detection unit periodically detects total power consumption of the
electronic apparatus and device information representing an operating
state of each device within the electronic apparatus. The power
consumption estimation unit estimates power consumption of the each
device based on the detected total power consumption and the detected
device information of each device.

Claims:

1. An electronic apparatus comprising:a battery for supplying electric
power to each device within said electronic apparatus;a detection unit
for periodically detecting total power consumption of said electronic
apparatus and device information representing an operating state of said
each device within said electronic apparatus; anda power consumption
estimation unit for estimating power consumption of said each device
based on said detected total power consumption and said detected device
information of said each device.

2. The electronic apparatus of claim 1, wherein said total power
consumption is approximated by the following equation: P ( t ) =
P 0 + j p j I j ( t ) ( 2 )
##EQU00011## where P is the total power consumption, P0 is power
consumption of each device during idling, Ij is device information,
and pj is a proportional coefficient with respect to said device
information Ij.

3. The electronic apparatus of claim 1, further comprising:a desired
operation time setting unit for setting a desired operation time of said
battery in response to a user's operation;a remaining battery capacity
detection unit for detecting the remaining capacity of said battery; anda
power consumption control unit for determining a range of target power
consumption based on the desired operation time of said battery set by
the desired operation time setting unit and said remaining battery
capacity detected by said battery capacity detection unit to control the
operating state of each device based on said power consumption of each
device estimated by said power consumption estimation unit so that the
total power consumption falls in the range of a target power consumption
when said total power consumption detected by said detection unit is out
of the range of said target power consumption.

4. The electronic apparatus of claim 1, further comprising:a battery
usable time presentation unit for determining an estimated value of said
total power consumption in each power mode based on the power consumption
of each device estimated by said power consumption estimation unit and
that estimates battery usable time in each power mode based on the
estimated value of said total power consumption to display the time in a
display screen.

5. The electronic apparatus of claim 1, further comprising:a first battery
extended time presentation unit that calculates battery extended time
when the supply of the electric power to the device is stopped based on
the power consumption of the device estimated by said power consumption
estimation unit, to display the battery extended time in a display
screen.

6. The electronic apparatus of claim 1, further comprising:a second
battery extended time presentation unit that monitors a use situation of
the device with respect to each process and that calculates the battery
extended time extendable when each process is stopped based on the power
consumption of the device estimated by said power consumption estimation
unit, to display the battery extended time in a display screen.

7. A method comprising:supplying electric power to each device within said
electronic apparatus by a battery;periodically detecting total power
consumption of said electronic apparatus and device information
representing an operating state of each device; andestimating power
consumption of each device based on said total power consumption of said
electronic apparatus and said detected device information of each device.

8. A computer readable medium having a computer program product for
controlling power in a battery-powered electronic apparatus, said
computer readable medium comprising:computer program code for supplying
electric power to each device within said electronic apparatus by a
battery;computer program code for periodically detecting total power
consumption of said electronic apparatus and device information
representing an operating state of each device; andcomputer program code
for estimating power consumption of each device based on said total power
consumption of said electronic apparatus and said detected device
information of each device.

Description:

PRIORITY CLAIM

[0001]The present application claims benefit of priority under 35 U.S.C.
§§120, 365 to the previously filed Japanese Patent Application
No. JP2007-261373 entitled, "Electronic apparatus, power control method
for electronic apparatus and program to be executed by computer" with a
priority date of Oct. 4, 2007, which is incorporated by reference herein.

BACKGROUND OF THE INVENTION

[0002]1. Technical Field

[0003]The present invention relates to power control in general, and in
particular to a method for controlling power consumption in a
battery-powered electronic device.

[0004]2. Description of Related Art

[0005]As more and more battery-powered electronic devices appear in the
market each year, users also expect those electronic devices to be
capable of being continuously powered by batteries for a longer time.
Thus, many methods of lengthening the battery usage time for
battery-powered electronic devices have been implemented. Most of those
methods are accomplished by taking advantage of various power saving
functions.

[0006]For example, one prior art relies on the determination of whether or
not processing can be performed based on the remaining battery capacity
and the power consumption. If the processing cannot be performed, a
function having the lowest priority is selected as an alternative target
function from the functions registered in a limited operation
information, and a function using the same constitutional requirements as
those of the alternative target function but requiring less power than
that of the alternative target function is selected as an alternative
function to replace the alternative target function registered in the
limited operation information. The priority of the alternative function
is also changed to a high value. Another prior art relies on a profile
for each application such that power is supplied only to an apparatus
according to a user's usage situation.

SUMMARY OF THE INVENTION

[0007]In accordance with a preferred embodiment of the present invention,
an electronic apparatus includes a battery, a detection unit and a power
consumption estimation unit. The battery supplies electric power to each
device within the electronic apparatus. The detection unit periodically
detects total power consumption of the electronic apparatus and device
information representing an operating state of each device within the
electronic apparatus. The power consumption estimation unit estimates
power consumption of the each device based on the detected total power
consumption and the detected device information of each device.

[0008]All features and advantages of the present invention will become
apparent in the following detailed written description.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]The invention itself, as well as a preferred mode of use, further
objects, and advantages thereof, will best be understood by reference to
the following detailed description of an illustrative embodiment when
read in conjunction with the accompanying drawings, wherein:

[0010]FIG. 1 is a block diagram of an electronic apparatus, in accordance
with a preferred embodiment of the present invention;

[0011]FIG. 2 is a detailed block diagram of the electronic apparatus from
FIG. 1, in accordance with a preferred embodiment of the present
invention;

[0012]FIG. 3 is a flow chart of a method for managing power, in accordance
with a preferred embodiment of the present invention;

[0013]FIG. 4 is a diagram showing one example of a desired battery
operation time setting screen;

[0014]FIG. 5 is a diagram showing an actually measured value and an
estimated value of power consumption when an electronic apparatus is
operated under battery power; and

[0015]FIG. 6 is a diagram showing one example of a power mode selection
screen and a device power consumption screen.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0016]FIG. 1 is a block diagram of an electronic apparatus capable of
being powered by a battery, in accordance with a preferred embodiment of
the present invention. As shown, an electronic apparatus 10 includes a
power control unit 1, a battery 2, a power consumption measurement unit
3, a central processing unit (CPU) 4 (device 1), a display 5 (device 2),
a hard disk drive (HDD) 6 (device 3), a network card 7 (device 4), an
external port 8, and an external device 9 (device 5).

[0017]The battery 2 supplies electric power to the electronic apparatus
10. The power consumption measurement unit 3 detects a voltage of the
battery 2, and measures a remaining battery capacity and total power
consumption P of the electronic apparatus 10 based on the detected
battery voltage to output a measurement result to the power control unit
1. The CPU 4 (device 1) executes various types of calculation processing
to control the units of the electronic apparatus. The display 5 (device
2) displays user information and the like. The HDD 6 (device 3) stores
various programs to be executed by the CPU 4. The network card 7 (device
4) executes data communication by radio. The external port 8 is an
interface to be connected to the external device 9 (device 5). The
battery 2 supplies the electric power to the external device 9 to be
connected to the external port 8.

[0018]The power control unit 1 can be made of a program module or a
hardware module. The power control unit 1 functions as a power
consumption estimation unit that periodically monitors the total power
consumption P of the electronic apparatus and device information
representing the operating states of the devices to estimate the power
consumption of each device in real time based on the total power
consumption P and the device information of each device. Moreover, the
power control unit 1 functions as a power consumption control unit that
calculates a range of target power consumption based on the desired
operation time of the battery 2 set in response to a user's operation and
a remaining battery capacity to control the power state of each device
based on the estimated power consumption of each device so that the total
power consumption falls in the range of the target power consumption when
the detected total power consumption is out of the range of the target
power consumption.

[0019]In addition, the power control unit 1 functions as a battery usable
time presentation unit that calculates an estimated value of the total
power consumption in each power mode based on the estimated power
consumption of each device and estimates battery usable time in each
power mode based on the estimated value of the total power consumption to
present the time to a user. Moreover, the power control unit 1 functions
as a battery extended time presentation unit that calculates battery
extended time in a case where the device or a process is stopped based on
the estimated power consumption of the device, to present the battery
extended time to the user. For the present disclosure, "the process" is
defined as a program or a service.

[0020]An estimation method of the power consumption of the devices by the
power control unit 1 will be described. The total power consumption P can
be represented as the sum of basic power consumption P0 and power
consumption PD of each device D, expressed by equation (A) as
follows:

P ( t ) = P 0 + D P d ( t ) ( A )
##EQU00001##

[0021]The power consumption PD of each device D can be approximated
by equation (1), when an index Ij (the device information
representing the operating state of each device) of the device to be
monitored is appropriately selected.

where PD0 is power consumption during the idling of the device D,
pj is a proportional coefficient with respect to the index Ij,
and the following equation results:

θ D = { 0 D is off 1 D is
on ##EQU00003##

[0022]When θD is also incorporated as one index into the second
term of equation (1), the power consumption PD of each device D can
be represented by equation (B) as follows:

P ( t ) = j .di-elect cons. D p j I j (
t ) ( B ) ##EQU00004##

[0023]Therefore, the total power consumption P can be approximated by
equation (2) as follows:

P ( t ) = P 0 + j p j I j ( t )
( 2 ) ##EQU00005##

[0024]In the present embodiment, the total power consumption P and the
appropriate index Ij (the device information) with respect to each
device are periodically monitored, and all the data from the start of
measurement is calculated by a minimum square process to obtain the basic
power consumption P0 and a maximum likelihood value of the
proportional coefficient pj. Specifically, when a matrix S and a
vector T are represented by equations (3) and (4) by the usage of the
total power consumption P and the index Ij at time tn,
respectively, a proportional coefficient p is obtained as represented by
equation (5).

[0025]The electric power P0 during the idling can be obtained by
setting I0(tn)=1 (for all n) in equations (3) and (4). When the
maximum likelihood value of equation (5) is substituted into the above
equation (1) with respect to each device, the estimated time of the power
consumption for each device can be calculated in real time.

[0026]In addition, the power consumption in an operating situation
different from the present situation can be estimated using equation (2).
Moreover, even when the external device 9 is newly connected and the
power consumption changes, an index concerned with this external device 9
is taken into the matrix S, the vector T and the proportional coefficient
pj, whereby the power consumption can subsequently be estimated.

[0027]With the present invention, it is assumed that the number of the
indexes for use is N, a storage capacity of the order of about N2/2
is required, and summation needs to be performed about N2/2 times
for each sampling.

[0028]Moreover, for each process that is being performed by the electronic
apparatus, the usage of each device, for example, the number of commands
from the CPU 4 for use in the process, an input/output data amount or the
like is recorded. Such a recorded value is multiplied by the proportional
coefficient pj obtained as described above, whereby the power
consumption to be consumed by the process can be estimated.

[0029]FIG. 2 is a detailed block diagram of an electronic apparatus
according to Embodiment 1. In Embodiment 1, the electronic apparatus is
applied to a battery-driven type notebook-size personal computer. As
shown, the electronic apparatus according to Embodiment 1 includes a CPU
11, a read-only memory (ROM) 12, a random access memory (RAM) 13, a HDD
14, a display 15, an optical drive device 16, a network card 17, an input
section 18, an universal serial bus (USB) port 19, a battery 20, a power
controller 21, a DC-DC converter 22, an AC adapter 23 and the like. These
units are connected to one another via a bus.

[0030]The CPU 11 has a function of controlling the whole notebook-size
personal computer by a multitask OS 14a stored in the HDD 14 connected to
the CPU 11 via the bus, and performing processing based on various
programs stored in the HDD 14. The ROM 12 stores a BIOS 12a, data and the
like. The RAM 13 provides a memory for use as a work area at a time when
the CPU 11 executes various programs.

[0031]The display 15 includes a liquid crystal display, a backlight, an
inverter for driving the backlight, a driver circuit for driving the
liquid crystal display, a video controller and the like. The liquid
crystal display has a function of displaying a menu, a status, display
transition and the like accompanying various types of processing of the
CPU 11. The video controller under the control of the CPU 11 controls the
inverter to adjust the luminance of the backlight, or sends a video
signal to the driver circuit to control the display of the liquid crystal
display.

[0032]The network card 17 is connected to a network such as internet to
perform data communication, or communicates with another apparatus by an
infrared ray.

[0033]The input section 18 is a user interface for a user to perform an
input operation, and includes a keyboard having various keys for
inputting characters, commands and the like, and a mouse for moving a
cursor on a screen or selecting various menus.

[0034]The HDD 14 has a function of storing the multitask OS 14a for
controlling the whole notebook-size personal computer, various drivers
14b, a power manager 14c for controlling the power consumption of the
notebook-size personal computer during battery driving, various
application programs 14d and the like.

[0035]The AC adapter 23 is connected to a commercial power source, and
converts an AC voltage into a DC voltage to output the voltage to the
DC-DC converter 22. The DC-DC converter 22 converts the DC voltage
supplied from the AC adapter 23 into a predetermined voltage to supply
electric power to each unit, and charges the battery 20. The battery 20
is charged by the DC-DC converter 22, and supplies the charged voltage to
each unit. The power controller 21 controls the operations of the battery
20 and the DC-DC converter 22. On receiving a request for the measurement
of a remaining battery capacity and a total power consumption P of the
battery 20 from the power manager 14c, the power controller 21 measures
the remaining battery capacity and the total power consumption of the
battery 20 to output the measurement result to the power manager 14c. The
battery 20 is used in a case where the AC adapter 23 is not connected to
any commercial power source.

[0036]A function realized in a case when the CPU 11 reads and executes the
power manager 14c stored in the HDD 14 will be described with reference
to FIGS. 3 to 5. The CPU 11 executes the power manager 14c to function as
a detection unit, a power consumption estimation unit, a desired
operation time setting unit, a battery capacity detection unit or a power
consumption control unit. In the following description, the function
realized by executing the power manager 14c by the CPU 11 will be
described in accordance with the power manager 14c as a main operation.

[0037]FIG. 3 is a flow chart of a method performed by the power manager
14c. FIG. 4 is a diagram showing one example of a desired battery
operation time setting screen displayed in the display 15 by the power
manager 14c. When a button or an icon (not shown) displayed in the disc
top of the display 15 is selected, the power manager 14c displays the
desired battery operation time setting screen in the display 15. In the
desired battery operation time setting screen, as shown in FIG. 4, the
present remaining battery capacity, the present power consumption, the
target power consumption, remaining battery time, and a desired battery
operation time input column 30 are displayed. The user operates the input
section 18 to input desired battery operation time in the desired battery
operation time input column 30, thereby setting the desired battery
operation time. The upper limit of the imputable desired battery
operation time is limited by the power consumption in an idle state, and
a minimum power has to be secured to such a degree that the user can work
without feeling any discomfort. Instead of the inputting by the user, the
user's desired battery operation time may be estimated in cooperation
with a schedule stored in a notebook-size personal computer.

[0038]In FIG. 3, when the driving of the battery is started in accordance
with the change (the turning-on of a power source, resume, AC adapter
disconnection or the like) of the power source state of the notebook-size
personal computer, the power manager 14c starts. Simultaneously with the
starting, the power manager 14c starts a timer to collect the device
information representing the operating situation of the device and the
total power consumption P at constant time intervals (about one to
several seconds) (step S1), and the power manager acquires the desired
battery operation time (step S2).

[0039]When a timer event is generated, the power manager 14c detects the
remaining battery capacity and the total power consumption P via the
power controller 21, and acquires the device information (a CPU operation
frequency, a CPU utilization, an HDD utilization, HDD reading bytes, HDD
writing bytes and the like) (step S3).

[0040]The power manager 14c determines the upper limit and the lower limit
of the target power consumption based on the detected remaining battery
capacity and the desired battery operation time (step S4). For example,
the upper limit of the target power consumption=(remaining battery
capacity-emergency power)/desired battery operation time, and the lower
limit of the scheduled power consumption=the upper limit of the scheduled
power consumption×95%.

[0041]Next, the power manager 14c updates the values of the matrix S and
the vector T from the measured value of the device information in
accordance with the upper equations (3) and (4) (step S5), and determines
whether or not the total power consumption P is in a range of the target
power consumption (the lower limit of the target power
consumption≦the total power consumption P≦the upper limit
of the target power consumption) (step S6). When the total power
consumption P is in the range of the target power consumption ("Yes" of
step S6), the processing returns to the step S3 to discontinue the
operation until the next timer event is generated.

[0042]When the total power consumption P is not in the range of the target
power consumption ("No" of the step S6), the power manager 14c calculates
the proportional coefficient (p=S-1T) for obtaining the estimated
power of each device by equation (5), and estimates detailed power
consumption concerned with each device, for example, the power
consumption per CPU utilization of 1%, the power consumption per HDD
utilization of 1%, the power consumption per HDD reading byte and the
like with respect to respective device information pieces (step S7).

[0043]Subsequently, the power manager 14c determines whether or not the
total power consumption P>the upper limit of the target power
consumption (step S8), and executes power consumption decrease control
(step S10) when it is determined that the total power consumption
P>the upper limit of the target power consumption ("Yes" in step S8).

[0044]In the power consumption decrease control, for example, the
following processing steps (i) to (iv) are performed to decrease the
power consumption: [0045](i) The operating state of the device in which
performance can be lowered to control the power consumption is changed
(e.g., the adjustment of display luminance, CPU frequency). [0046](ii)
The power of an unused device is stopped. In (i)-(ii), the amount of the
power consumption to be decreased by the change of the operating state
can be predicted in advance based on the estimated result of the power
consumption of each device. Therefore, the devices are selected in order
from a device having little influence on the user, until the target power
consumption is reached, and then the operating state of the selected
device is changed. [0047](iii) If the target power consumption cannot be
achieved even when steps (i)-(ii) are performed, the utilizations of the
CPU 11 and the I/O of the process that is being operated are obtained to
estimate the power consumption for each process. When the power
consumption is large in a background process having little influence on
the productivity of the user, for example, a maintenance task, the
execution of such a process is temporarily stopped. [0048](iv) When the
target power consumption cannot be achieved even when step (iii) is
performed, the utilizations of the CPU 11, the HDD 14, the network card
17 and the like are controlled so as to fall in the range of the target
power consumption. The respective utilizations are distributed in
accordance with the past history, and can be calculated back from the
target power consumption. In this case, a resource is preferentially
assigned to the process used by the user in the foreground.

[0049]When it is not determined that the total power consumption P>the
upper limit of the target power consumption ("No" in the step S8), that
is, it is determined that the total power consumption P<the lower
limit of the target power consumption, the power manager 14c executes
power consumption increase control (step S9). In the power consumption
increase control, processing reverse to the above processing steps
(i)-(iv) are performed to improve the performance. When the desired
battery operation time elapses, or when the AC adapter 23 is connected to
the commercial power source to change the driving to AC driving, the
power manager 14c stops the operation thereof.

[0050]FIG. 5 shows the actually measured value of the power consumption
when the electronic apparatus of the present embodiment is used in a
battery driven manner for 6,000 seconds, and an estimated value obtained
by a method according to the present invention. In FIG. 5, the abscissa
indicates time (s), and the ordinate indicates the power consumption (W).
FIG. 5 shows a case when the CPU operation frequency, the CPU
utilization, the HDD utilization, HDD reading bytes and HDD writing bytes
are used as the device information in estimating the power consumption.
The estimated value substantially matches the actually measured value.

[0051]Next, a specific calculation example of a method for estimating the
power consumption of the device will be described. The total power
consumption P is approximated by equation (11), and all the indexes
Ij (the device information) and the total power consumption P are
repeatedly measured. When the measured value of the total power
consumption P acquired at the time tn, the sum of square errors is
represented by equation (12).

[0052]A combination to minimize equation (12) is supposed to be the
maximum likelihood value of the proportional coefficient pj, and
equation (13) can be derived from equation (C). When the matrix S and the
vector T are represented by equations (14), (15), a set of proportional
coefficients p can be obtained by equation (16).

[0053]To simplify the description, a system having three parts, such as
the CPU 11, the display 15 and the hard disk (HDD) 14, is utilized. The
CPU 11 has two operation frequencies f0, f1 at low and high
speeds, and consumes electric powers different from each other in
accordance with the respective operation frequencies, and the sum of the
electric power during the idling and the electric power proportional to
the utilization can be approximated with respect to the respective
operation frequencies f0, f1.

[0054]In the display 15, a backlight can be adjusted in two stages, that
is, bright and dark stages, and a substantially constant electric power
P0Display or P1Display is consumed in each mode. The
HDD 14 can consume the electric power in proportion to the utilization
time ratio, the amount of data to be written and the amount of data to be
read, respectively, in addition to the electric power during the idling.

[0055]At this time, the total power consumption P, power consumption
PCPU of the CPU 11, power consumption PDisplay of the display
15 and power consumption PHDD of the HDD 14 can be represented by
equation (17).

where PiCPU: the power consumption during an idling operation at
a frequency fi; [0056]UCPU: the CPU utilization;
[0057]PiCPU: the proportional coefficient of the utilization
with respect to the power consumption: [0058]UHDD: the utilization
time ratio of the HDD; [0059]W: the amount of the data to be written;
[0060]R: the amount of the data to be read; and [0061]u, w and r: the
proportional coefficients.

[0062]When equation (17) is adapted to the format of equation (11), the
following equation (18) can be represented.

[0063]The frequency and the utilization of the CPU 11, the luminance of
the display 15, the utilization, the amount of data to be written and the
amount of the data to be read in the HDD 14, and the total power
consumption P (Power) are periodically measured, and the measurement
results shown in Table I can be obtained.

[0064]The measurement results shown above in Table I are substituted into
equations (14) to (16) to obtain solutions as follows:

P0CPU=8.15 W, p0CPU=24.7 mW/%

P1CPU=9.95 W, p1CPU=69.8 mW/%

P0Display=8.22 W, p1Display=10.24 W

P0HDD=-14.06 W, u=9.87 mW/%, r=152 mW/MB

w=247 mW/MB

[0065]A correlation between the predicted value and the actually measured
value using these coefficients is a considerably high value of 99.97%,
and the whole model validity is confirmed. On the other hand, as seen
from P0HDD of a negative value, non-fluctuation components
P0CPU, P1CPU, P0Display,
P1Display and P0HDD have results that do not have any
reliability. In actual, the standard error of P0HDD is much larger than
the result, is and as to the other values, any standard error cannot be
calculated. This indicates that the non-fluctuation components cannot be
separated. When data is classified for the same non-fluctuation component
and the estimated values are separately obtained, such uncertainty can be
eliminated. In the above case, the data is classified into four states,
that is, (1) low speed CPU-dark backlight, (2) high speed CPU-dark
backlight, (3) low speed CPU-bright backlight and (4) high speed
CPU-bright backlight. The calculation results are obtained as follows.

[0066](1) Low Speed CPU-Dark Backlight

P0CPU+P0Display+P0HDD=2.21 W,
p0CPU=21.7 mW/%

u=13.4 mW/%, r=146 mW/MB, w=284 mW/MB

[0067](2) High Speed CPU-Dark Backlight

[0068]Lack of data

[0069](3) Low Speed CPU-Bright Backlight

P0CPU+P1Display+P0HDD=4.45 W,
p0CPU=25.7 mW/%

u=9.24 mW/%, r=125 mW/MB, w=222 mW/MB

[0070](4) High Speed CPU-Bright Backlight

P1CPU+P1Display+P0HDD=6.21 W,
p1CPU=68.5 mW/%

u=9.02 mW/%, r=154 mW/MB, w=271 mW/MB

[0071]When the data is beforehand classified for each system state and
calculated in this manner, a calculation amount can largely be decreased.
In the first calculation, 10×10 ten symmetric matrix elements need
to be obtained to obtain ten unknown quantities, and 55 product sum
operations are required for acquiring each data. In the calculation after
the classification, the non-fluctuation components added up to obtain
five unknown quantities. Therefore, the number of the calculating
operations is sufficiently 15. The non-fluctuation components cannot be
separated, but idling power in each state is obtained, and hence any
practical problem is not generated.

[0072]On the other hand, the number of the data after classified
decreases, and hence error increases. In actual, in the above example,
there are fluctuations in the values of u, r and w in the above states
(1), (3) and (4). Moreover, in the state (2), only four data are given
with respect to five unknown quantities. Therefore, even the estimated
value is not obtained. However, in an actual operation, much more
measurement operations are performed in real time, and hence the error is
sufficiently converged and decreases.

[0073]As described above, according to Embodiment 1, the power manager 14c
periodically detects the total power consumption of the apparatus and the
device information representing each device operating state, and
estimates the power consumption of each device in real time based on the
detected total power consumption of the apparatus and the device
information of each device. Therefore, in the battery-driven type
electronic apparatus, the power consumption of each device constituting
the electronic apparatus can be estimated with high accuracy.
Additionally, even when the power consumption largely fluctuates in
accordance with the additional installation of devices or the change of
use cases, quantitative power control can be performed by accurately
estimating the power consumption of each device from its power state and
utilization.

[0074]Moreover, according to Embodiment 1, when the total power
consumption is P, the power consumption of each device during the idling
is P0, the device information is Ij, and the proportional
coefficient with respect to the device information Ij is pj,
the total power consumption P can be approximated by the above equation
(2). Therefore, the power consumption of each device can be estimated by
simple calculation.

[0075]Furthermore, according to Embodiment 1, the power manager 14c
calculates the range of the target power consumption based on the desired
operation time of the battery 20 set by the user and the remaining
battery capacity. When the total power consumption P is out of the range
of the target power consumption, the operating state of each device is
controlled based on the estimated power consumption of each device so
that the total power consumption P is in the range of the target power
consumption. Therefore, even when the power consumption largely
fluctuates in accordance with the additional installation of the device
and the use situation, dynamic power control can quantitatively be
performed. Additionally, in Embodiment 1, the power consumption of the
device is estimated in real time. Therefore, when the performance and the
amount of the operation to be executed are dynamically changed, the best
performance can be provided in accordance with the battery driving time
required for the user. Moreover, the shortage of the electric power due
to rapid power control can be compensated by temporary discontinuation or
delaying of the process that is being executed, limitation of an access
to a device that consumes large electric power and the like. On the other
hand, when the target power consumption is below the actual power
consumption, surplus power can be used for improving the performance of
the system.

[0076]In Embodiment 1, when the measured total power consumption P is not
in the range of the target power consumption, the power manager 14
automatically controls the power consumption so that the total power
consumption P falls in the range of the target power consumption. On the
other hand, in Embodiment 2, the power manager 14c presents, to a user,
battery usable time for each power mode and power consumption for each
device or process, to facilitate user's setting of the power consumption
during the use of a battery.

[0077]In Embodiment 2, a CPU 11 executes the power manager 14c to function
as a battery usable time presentation unit, a first battery extended time
presentation unit or a second battery extended time presentation unit. In
Embodiment 2, when the driving of the battery is started, in the same
manner as in Embodiment 1, the power manager 14c starts a timer, collects
device information and total power consumption P at constant time
intervals, substitutes the measured values of the device information and
the total power consumption P into the above equations (2), (3) to
calculate matrix S and vector T in real time, and estimates a
proportional coefficient (p=S-1T) and the power consumption of each
device.

[0078]FIG. 6 is a diagram showing one example of a power mode (profile)
selection screen and a device-process power consumption screen. In a desk
top of a display screen of a display 15, a button (not shown) or an icon
(R) (not shown) for changing a power state is displayed. When a user
intends to lengthen battery driving time or is dissatisfied with the
performance of a personal computer, the user operates an input section 18
to select this button or icon (R). Then, the power manager 14c displays a
power mode selection screen P1. The power mode selection screen P1
displays a battery usable time (a predicted value) list 41 in power modes
(first to sixth modes) and a detailed information button 42 for
displaying the device-process power consumption screen. For example, the
battery usable time (the predicted value) when the sixth mode (Maximum
Battery Life) is selected is 3.35 h.

[0079]The user can select the power mode in this list 41. The power
manager 14c applies the present use situation (device information, the
estimated value of the power consumption of each device) to the device
setting defined in each power mode to obtain the predicted value of the
total power consumption in each power mode, estimates the battery usable
time, and displays, in the list 41, the battery usable time (the
predicted value) in each power mode (the first to sixth modes). In
consequence, the user can select the power mode in consideration of the
battery usable time.

[0080]When the detailed information button 42 is selected, the
device(process power consumption screen is displayed. In the
device(process power consumption screen, the display of the device or the
process can be switched with a selection button. When the device is
selected, a device(process power consumption screen P2 is displayed. When
the process is selected, a device(process power consumption screen P3 is
displayed.

[0081]The device-process power consumption screen P2 displays the
estimated power consumption of a detachable/attachable device(=a device
in which power supply can be stopped) and the battery life in a case
where the device is detached or attached. The power manager 14c
calculates the battery life after the detachment of the device based on
the current status (the device usage and the estimated power consumption)
of the detachable/attachable device. For example, in the example shown in
the drawing, when the network card 17 is detached or attached, power
consumption of 3.2 W can be saved, and the battery life can be extended
as much as 45 minutes. Moreover, in the device (process power consumption
screen P2, the power manager 14c displays the changes of the power
consumption and the battery life due to the changes of the settings of
the luminance of the backlight of the display 15, the performance of the
CPU 11 and the like. When the user moves the slider, the luminance of the
backlight of the display 15 and the performance of the CPU 11 can be set.

[0082]The device-process power consumption screen P3 displays the power
consumption due to the execution of processes and the battery life after
stopping the process. The power manager 14c monitors device usages for
each process, and calculates and displays the estimated power consumption
and the battery life extendable at a time when the process is stopped.
For example, when Application B is stopped, the 3.2 W of power can be
saved, and the battery life can be extended as much as 45 minutes.

[0083]Thus, when the device-process power consumption screens P2, P3 are
presented to the user, the user can set the performance in accordance
with the necessary battery life. For example, to extend the battery life,
an unnecessary device is removed, and the performance of the CPU 11 and
the luminance of the backlight of the display 15 are lowered, or the
unnecessary process is stopped, whereby the power consumption can be
decreased.

[0084]As described above, according to Embodiment 2, the power manager 14c
predicts the total power consumption and estimates battery life in each
power mode based on the power estimation of each device and displays them
in the display screen. Hence, the criterion for the user to select the
power mode is clarified.

[0085]Moreover, according to Embodiment 2, the power manager 14c
calculates the battery extended time in a case where the power supply to
the device is stopped based on the estimated power consumption of the
device, to display the time in the display screen. Therefore, the user
can remove the device that consumes large power, to save unnecessary
power.

[0086]Furthermore, according to Embodiment 2, the power manager 14c
monitors the device usages in each process, and calculates the battery
extended time extendable at a time when each process is stopped based on
the power estimation of each device to display the time in the display
screen. Therefore, the user can stop the process that consumes large
power, to avoid the unnecessary power consumption.

[0087]As has been described, the present invention provides a method and
apparatus for controlling power in a battery-powered electronic device.

[0088]It is also important to note that although the present invention has
been described in the context of a fully functional system, those skilled
in the art will appreciate that the mechanisms of the present invention
are capable of being distributed as a computer program product.

[0089]While the invention has been particularly shown and described with
reference to a preferred embodiment, it will be understood by those
skilled in the art that various changes in form and detail may be made
therein without departing from the spirit and scope of the invention.